In the fields of surgery, dentistry and orthodontia, professionals often have a desire to reach interior portions of a person's anatomy to grasp objects, tissue, etc. Many prior art devices to achieve such objectives are linear with grasping jaws, while still others have a flexible portion that facilitates some angular adjustments. Such tools, however, are often complicated in terms of construction, often employing rails and jointed connections that rotate relative to each other to facilitate desired flexibility of the tool along at least an extent thereof. A simpler, cost effective, and versatile tool is therefore desired that can facilitate such professional's procedures involving reaching into interior portions of a person's anatomy to grasp objects, tissue, etc.
Occluded blood vessels can be caused by a blood clot (i.e. thrombus) that forms in the blood vessel or by a blood clot that travels downstream (i.e. embolus). The blockage disrupts blood flow, which prevents oxygen and nutrients from being delivered to their intended locations. Tissue distal of a blood clot that is deprived of oxygen and nutrients can no longer function properly. For every minute that treatment is delayed, additional cellular death of critical tissue can occur.
Current technology for blood flow restoration, for example for treating cerebral arteries occluded by thrombi, can often take hours to reestablish flow in the artery, and can lead to unintended complications. Apparatuses and methods for treating cerebral thrombi are often ineffective or only partially effective at resolving thrombus removal, and may result in distal embolization or embolization of uninvolved arteries. For example, some current devices are designed to pierce through a thrombus, or are designed to deploy completely distal of the thrombus before engaging the thrombus. These devices can often fail to capture all of a thrombus, can damage vessel walls distal of a thrombus, can be difficult to maneuver, can unintentionally dislodge portions of a thrombus prior to capture, and/or can take significant amounts of time to restore blood flow. Acute stroke is one of the leading causes of death worldwide; an estimated 85% of acute strokes are caused by cerebral ischemia. About 30% to 40% are large-vessel occlusions amenable to intervention.
A stroke is caused by a rupture or an occlusion of a blood vessel which leads to oxygen deprivation in the brain. In the United States, nearly eight hundred thousand people suffer a stroke each year, and over one hundred and forty thousand people die from strokes each year. Stroke is the leading cause of serious, long-term disability in the United States and the third leading cause of death. Approximately three-quarters of strokes in the United States are first attacks and approximately one-quarter are recurrent attacks. Eighty seven percent are ischemic in nature, meaning that they are caused by a restriction, obstruction, or blockage in the blood supply of the patient, and thirteen percent are hemorrhagic, meaning that they are caused by excessive bleeding. The economic cost of stroke to the United States is over forty billion dollars per year. The direct costs of medical care and therapy are almost thirty billion dollars per year.
It is well known in the art that the extent to which treatment of a stroke is successful in preventing death and/or in reducing the consequent damage to a patient is largely influenced by the time which elapses between the onset of the stroke and the proper treatment of the stroke. The elapsed time is a function of not only whether or not a patient is able to get to a medical facility or hospital, but also the nature of the stroke and whether or not the particular medical facility or hospital to which the patient is initially brought is best equipped to treat the stroke. The capability of the medical facility to treat the particular stroke may not be known until the patient is properly evaluated and analyzed.
Blood clots or emboli to the pulmonary arteries of the lung, the brain, the peripheral arteries of the extremities, in the venous system, or in dialysis access vessels are potentially life and/or limb threatening conditions. Delivered systemically, thrombolytic drugs typically require several hours to days to accomplish dissolving these clots. In cases where time is of the essence, such as cases where an arterial thromboembolism is causing severe tissue ischemia (e.g., an evolving stroke or an evolving myocardial infarction) the time which may be required for the thrombolytic drugs to fully lyse or dissolve the blood clot and restore arterial blood flow may be too long to avoid or minimize the impending infarction. Thrombolytic drugs also have an approximately 5% incidence of major complications such as hemorrhage and stroke. Conventional devices are often difficult to advance into curved and tortuous vessels such as the pulmonary arteries. While devices available in the marketplace may break up a clot and suction the resulting particles out, they often infuse large volumes of fluid as part of their action, which may be physiologically difficult to handle for the patient.
There is a great need for improved devices, device systems, and methods for increasing blood flow through a blood vessel as described herein. None of the existing medical mechanical thrombectomy devices address all necessary needs to date. The high prevalence and high rates of death and disability caused by ischemic stroke call for the urgent need for more effective and accessible therapeutic alternatives to the population at risk.
There is therefore a need for devices that can rapidly and safely be used during intravascular interventions to prevent distal embolization by capture of blood clots or atheromatous material.
Transluminal, catheter-based interventional procedures are highly operator-skill-dependent, and can be difficult or impossible to perform in small or tortuous blood vessels. None of the transluminally deployable clot capturing type of catheters are perfectly designed to address ischemic strokes because, while they are typically capable of removing an offending blood clot without the need for suction or application of energy (e.g., laser, ultrasound) which could be injurious to the delicate, small blood vessels of the brain, they are a) not equipped with appropriate guidewire passage lumens to allow them to be passed over previously inserted, small-diameter (e.g., 0.006-0.018 inch) guidewires, b) they are not adapted for rapid exchange over a guidewire of standard length (e.g., a guidewire which is less than twice the length of the catheter) and c) the clot capturing receptacles of these catheters are not optimally constructed and configured for removal of clots from very small blood vessels as are typically found in the brain.
Major disadvantages of existing mechanical thrombectomy devices include that they often can only capture and remove embolus that are firm and can be held together as one piece and are not capable of capturing small emboli that break off from a larger embolus, and can lead to complications such as blockage of distal smaller vessels, vessel dissection, perforation and hemorrhage arise as a result of over-manipulation in the vessel.
Moreover, some existing devices may capture an embolus, but then lose grasp of it so that it migrates and deposits it incidentally in another area of the neurovasculature, creating the potential for a new stroke in a different part of the neurovasculature. Existing mechanical thrombectomy devices are also constructed of two or more distinct pieces that require either joints or bonding between a delivery system and a treatment device, with this connection presenting occasions of unintentional separation of the two pieces, thus leaving the treatment device in the body during embolus retrieval. Also, the treatment portion of conventional mechanical thrombectomy devices tend to be larger than the delivery system.
Guide wires stiff enough to penetrate hard occlusions have the disadvantage that their inflexibility and straight tips make navigating through tortuous vessels difficult and increase the risk of vessel perforation.
Conventional therapies to treat stroke include thrombolytic therapy and catheter directed thrombectomy (CDT). Drawbacks of thrombolytic therapy include hemorrhagic risk. Conventional CDT systems often employ an introducer sheath or catheter to the target site, with such larger introducer sheaths increasing the risk of trauma to the patient, and being harder to navigate through the vessels.
Conventional catheter devices use a shaft comprising an outer tube connected to the sheath and an inner shaft such that the proximal movement of the sheath is accomplished by imposing an endwise tension on the outer tube, with the inner shaft carrying an endwise compression stress. Such a catheter effectively has telescoping inner and outer tubes, with a deployable wire nest being radially constrained by the outer tube. Retraction of the outer tube removes the constraint on the clot removal device and permits it to expand to its deployed configuration. One disadvantage is that in use, such devices require the medical practitioner to maintain the device in an unchanged axial disposition relative to the site in the body of the patient, while pulling back on the outer tube of the shaft to release the expandable portion of the device. This pulling back of the outer tube requires relative movement of the outer tube in the bodily lumen (or guide catheter) in which it has been advanced to the site of the thrombus. Any friction or resistance to axial movement of the outer tube in the lumen in which it is located hinders the objective of maintaining the device in a precise disposition.
One conventional device is the Merci retrieval device made by Concentric Medical, and another is sold by Penumbra, Inc., which employs suction to pull out a clot. Both of these devices are often unsuccessful in their intended functions. Recent reports indicate that the Trevo and Solataire devices, also of similar operation in terms of employing outer and inner luminal movements, are superior in various respects to the Merci and Penumbra devices. All of these devices, however, rely upon a dual lumen translational construction to achieve employment of a thrombus capture device. The present invention addresses this issue by providing a distinctly different and better way to achieve the objective of safely, promptly and effectively capturing a thrombus and reducing its volume while being conveyed out of the body.
Existing common concerns of physicians who practice angioplasty include: concern that the thrombectomy device may capture an embolus, only to lose hold of it and accidentally deposit it in another area of the neurovasculature; concern that the device may not be able to capture a ‘break-off’ piece of the embolus, which may migrate further into the neurovasculature; concern that the relatively large device may prevent it from accessing and treating clots in small-diameter vessels; and concern that the devices usually require adhesive joining or bonding between the delivery system and the treatment device. In the latter case, in some instances a concern is that the adhesive bonding may fail, presenting the possibility that the pieces may separate, presenting a serious complication in the procedure. These concerns are addressed by the present invention as the pair of netting structures ensures secure capturing of a thrombus without the threat that there would be any break off pieces of the emboli. The small profile provided by the present embodiments of the present invention provides for a way to access even narrow, convoluted blood vessels and to capture an emboli in a straightforward netting operation with the operation of a haptic friendly trigger operation of a handle by a surgeon.
A large number of medical procedures require the use of a medical device to remove an obstruction from a body lumen, vessel, or other organ. An inherent risk in such procedures is that mobilizing or otherwise disturbing the obstruction can potentially create further harm if the obstruction or a fragment thereof dislodges from the retrieval device. If a particle or the obstruction breaks free from the device and flows downstream, it is highly likely that the particle or obstruction will become trapped in smaller and more tortuous anatomy. In many cases, the physician will no longer be able to use the same retrieval device to again remove the obstruction because the size of the device may prevent advancing the device to the site of the new obstruction. Such concerns are addressed by the present invention as the netting structure of preferred embodiments captures the entire thrombus and thus avoids the threats associated with breaking up of the thrombus as is a common concern with conventional devices.
A variety of mechanisms have been employed to steer conventional catheters, with some specialized catheter systems having dozens of pull wires being articulated by a dedicated motor attached to the proximal end. Alternative articulation systems utilize electrically actuated shape memory alloy structures, piezoelectric actuation, phase change actuation, and the like. These steerable systems increase the complexity and price of devices and have questionable benefits in practice. As articulation systems for catheters get more complex, it can be more and more challenging to maintain accurate control over these flexible bodies. For example, pull wires that pass through bent flexible catheters often slide around the bends over surfaces within the catheter, with the sliding interaction extending around not only bends intentionally commanded by the user, but also around bends that are imposed by the tissues surrounding the catheter. The result is that existing devices are deficient in various respects, hampering the ability of a surgeon to promptly advance a tool through a blood vessel to the site of a thrombus, and to then effectively capture the entire thrombus/emboli in a manner that does not pose a risk that pieces of the thrombus/emboli will dislodge and potentially cause other problems. Existing devices further do not permit the thrombus to be reduced inside a secure capturing confine so that damage to the vessels is avoided when attempting to remove the thrombus from the blood vessels.
In still other procedures that do not involve a thrombus in brain tissue, for example, the treatment of deep vein thrombosis (DVT), which results from a clot that forms in one of the large veins of the leg leading to venous hypertension and inflammation, a need exists for a better system and method to remove occlusions. Venous thrombosis can occur in healthy as well as sick individuals. A complication most commonly associated with venous thrombosis is the condition known as “pulmonary embolism.” A pulmonary embolus is actually a clot that has broken free from a vein wall and has traveled to the pulmonary artery, and then, if not removed, to a lung. When an embolus blocks a blood vessel in the lung, breathing is compromised and death may ensue. Accordingly, early treatment of DVT is desirable.
The longer the occlusion remains, the more risk of damaging the valves of the vein that normally stop blood from flowing backwards. A confluence of symptoms comprised of chronic pain, swelling, skin ulcerations and pain can develop that can markedly reduce the quality of life. A rapid, direct method to remove clots in the leg, with minimal lytic drugs, is needed to treat DVT patients. Such a device and method is provided by the present invention.
Over the last 10 years there has been major technological breakthrough for the mechanical thrombectomy devices, starting with MERCI® retriever and reaching stent retriever devices (e.g. SOLITAIRE® and TREVO®). As compared to such devices, however, the present invention provides a device and related method to provide a more flexible profile, allowing easier navigation and faster access to vascular occlusion site. The importance of agility in the endovascular treatment in order to prevent irreversible damage to a person's brain is immense and the provision of a device that is simple, easily employed and that can be used well within the 3-hour time period after a stroke to save the person's life and brain is a central focus of the present invention.